(a) Field of the Invention
The present invention relates to a method of direct communication between terminals (or devices or equipment). More particularly, the present invention relates to a method of providing communication service between terminals in a wireless communication system.
(b) Description of the Related Art
A method of establishing a direct link between terminals to provide a proximity-based service in a wireless communication system is currently being discussed in IEEE 802.11(Pre-association discovery; PAD), 802.15 (TG8, Peer Aware Communication; PAC), 802.16 (GRIDMAN TG), and 3GPP (Proximity-based Service; ProSe).
Services through a direct link between terminals now under discussion can be used for public safety, disaster relief, proximity-based services (LTE Device to Device Proximity Discovery), etc. To establish a direct link, the possibility of establishing a direct link is assessed by discovering for neighboring terminals.
However, the prior art only describes methods for performing device discovery operations (e.g., transmitting a reference signal, reporting after signal strength measurement, and so on) upon a request from a base station. According to the prior art, a neighboring device discovery will affect existing services between a base station and a terminal. Particularly, if resources to be provided to lower-level terminals of a base station (e.g., terminals registered with a base station) are used as resources for device discovery (for establishing a direct link), the prior art can bring about many problems.